Pioglitazone: no cancer for 3 years

A three-year study (2005-2008) undertaken on 204 subjects who had impaired glucose tolerance (IGT), a pre-diabetic stage, and who were on pioglitazone drug alone did not find any case of bladder cancer.

The primary objective was, however, to see if the drug in addition to lifestyle modifications helped in preventing subjects with IGT from becoming diabetic.

The study was published in March 2009 in Diabetologia journal and was undertaken by a team of diabetologists led by Dr. A. Ramachandran of India Diabetes Research Foundation, Chennai and Dr. A. Ramachandran’s Diabetes Hospital, Chennai.

The study gains significance at this point in time as the Health Ministry’s decision of June 18 to ban the oral anti-diabetic drug pioglitazone on safety grounds has become highly controversial. Following protests from doctors, the government constituted an expert committee of 12 doctors which on July 11 strongly recommended that the ban be revoked.

The highlight of the study is that it was a randomised, double-blind study. All subjects had IGT and one arm with 203 subjects undertook lifestyle modifications and got a placebo (dummy drug), while the other group (204 subjects) got pioglitazone in addition to lifestyle modifications.

The pioglitazone arm got 15 mg a day of the drug for the first six months, which was later increased to 30 mg a day. Subjects complained of giddiness when the dose was increased to 40 mg a day. Hence, 30 mg a day was continued for the remaining duration of the study.

At the end of the trial period, both arms reported two cardiac events but there was no incidence of bladder cancer in any of the subjects.

“Other studies take the data from the database and look for a link between pioglitazone and bladder cancer,” Dr. Ramachandran said. “Though they look for prescription the adherence rate cannot be measured. But ours was a randomised, double-blind study and all subjects were monitored for the entire duration of the study [six months].”

Since the arm that received the drug was on just one anti-diabetic drug, it was easy to assess the effect and risk more effectively, he said.

Is three years follow up enough to rule out bladder cancer incidence in patients who received the drug? Are there any bio markers available to test whether these patients would be prone to bladder cancer in future? Mere absence evidence(of overt symptoms) is not evidence of absence.